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# FLETCHER

Arduino Library for Fletcher's checksum


## Description

This library provides a Fletcher checksum of a data array.

Fletcher's checksum is in general faster than CRC but possibly not as 
good in detecting errors.
See https://en.wikipedia.org/wiki/Fletcher%27s_checksum for details.

Relates to https://github.com/RobTillaart/CRC

Use https://github.com/RobTillaart/printHelpers to print the Fletcher64().

Tested on Arduino UNO only.


## Interface

The functions are straightforward, however one should define **length**
in terms of the data type and optional pad it with zeros.

A string "abcdef" has length 2 for **fletcher64()**.

- **uint16_t fletcher16(uint8_t \*data, uint16_t length)** idem.
- **uint32_t fletcher32(uint16_t \*data, uint16_t length)** idem.
- **uint64_t fletcher64(uint32_t \*data, uint16_t length)** idem.

TODO - class version.


## Operation

See examples.


## Future ideas

- improve documentation
- test other platforms
- Class versions
  - incremental calculate e.g. for a stream.
  - similar to CRC classes
- look for optimizations 
- Fletcher24 ? and others?
- generic FletcherN(). for N = 1..32